Astigmatism results from variations
or irregularities in the curvature of the cornea or lens. In the
astigmatic eye, the cornea is oval or football-shaped as compared
to the normal cornea, which is round. In the astigmatic eye, the
variations in the curvature of the cornea prevent all the light
rays of a source from focusing at a single point, thus causing
blurred vision. Astigmatism is a common problem; in many people it
is mild and does not need correction. It is thought to be
hereditary and runs in families. Astigmatism may also occur with
other refractive disorders; approximately half of all nearsighted
people, for example, also have astigmatism.
Astigmatism can also be acquired due
to certain diseases and disorders. These include keratoconus,
chalazion, drooping eyelid and lenticonus, among others.
Symptoms
blurred vision, both near and distant
eye strain, headaches
frequent squinting, which may occur as a result of eye strain
and headache
What your doctor looks for
Your doctor may examine your eyes
with a retinoscope to check for astigmatism, measure the curvature
of your cornea using a keratometer, or ask you to read the eye
chart while looking through a device called a phoropter to
determine what type of glasses or contacts might correct your
astigmatism.
Treatment
Astigmatism can be corrected with
glasses, certain contact lenses or surgery.
When to call your doctor
Schedule an eye exam if your vision
is blurred or if your child complains of blurred vision, eye strain
or headache.
Prognosis
Astigmatism may increase slowly as a
person ages but usually remains stable throughout life. The
prognosis for excellent vision is good for people with astigmatism
with glasses or contact lenses alone, unless it is caused by
certain eye diseases and disorders that may require surgical
correction like keratoconus or cataract.
Additional information
For more information about
astigmatism, you can contact:
National
Eye Institute
2020 Vision Place
Bethesda, MD 20892-3655
Phone: (301) 496-5248 http://www.nei.nih.gov
The National Eye Institute is part
of the National Institutes of Health. The National Eye Institute
also offers a list of national organizations that are related to
eye health, which is available at http://www.nei.nih.gov/health/organizations.htm.
Wilmer Eye
Institute
Johns Hopkins Hospital
600 N. Wolfe St.
Baltimore, MD 21287
Phone: (410) 955-5080 http://www.wilmer.jhu.edu/
American
Academy of Ophthalmology
P.O. Box 7424
San Francisco, CA 94120
Phone: (415) 561 8500 http://www.aao.org
